How Big Do Axolotls Get? 

Axolotls (Ambystoma mexicanum) are salamanders, which are amphibians that appear similar to lizards. In the Nahuatl language of the Aztecs, “axolotl” means “water dog.” They are also sometimes called Mexican walking fish, but of course they are not actually fish, even though axolotls remain in the water their entire lives. As adults, axolotls retain many of their juvenile traits. However, do they remain their juvenile size? Keep reading to learn more about these unique salamanders and find out how big axolotls get.

The Axolotl’s Natural Habitat

The axolotl is native to Mexico’s Central Valley. They originally lived in Lake Chalco and Lake Xochimilco in the Basin of Mexico. However, Lake Chalco was drained to reduce flooding in the region. So axolotls can now only be found in Lake Xochimilco, south of Mexico City.

Their habitat in Lake Xochimilco has also become degraded due to the introduction of invasive species and pollution. The IUCN currently lists wild axolotls as Critically Endangered. However, these permanently smiling salamanders are popular in the pet trade, and some sources estimate there are at least a million axolotls in captivity worldwide.

Amphibians That Never Grow Up

Most salamanders go through the process of metamorphosis similar to the process of tadpoles turning into frogs. During this process, they not only develop limbs, they also develop eyelids and lungs to breathe air. So, when salamanders reach adulthood, they are able to live on land.

However, axolotls do not normally go through metamorphosis, remaining fully aquatic their entire lives. They are neotenic or paedomorphic, meaning they keep larval characteristics as sexually mature adults. Axolotls retain their feathered, external gills and long tadpole-like tails for swimming. Their skeleton remains mostly cartilage, never fully turning to bone. They also grow lungs and limbs, which are functional but underdeveloped.

Like other salamanders, axolotls also have regenerative abilities. They can regrow their tails, fins, limbs, spinal cords, gills, lungs, liver, teeth and jaws, ovaries, eye lenses, heart and part of their brains. Axolotls can repair any injury without scarring. Scientists have found that axolotls forced to go through metamorphosis using thyroid hormones have limited regeneration ability and a reduced lifespan.

How Big Are Fully Grown Axolotls? 

Axolotls are around 0.38 inches to 0.5 inches when they hatch. They look like tadpoles without limbs, but they grow relatively quickly. By 2-3 weeks of age, they begin to develop lizard-like limbs. In the wild, their skin is olive, grey, or dark brown with black spots, but in captivity, they can be a wide range of colors, including gold, white (albino), pink (leucistic), or multicolored.

Axolotls grow to reach about 12 inches, but most average around 9 inches. Their heads are about 1.6–1.8 inches and their tails measure between 2.4–3.0 inches. Female axolotls are larger than males. The females weigh between 6.0–6.3 ounces, while males weigh between 4.4–4.6 ounces. They reach sexual maturity between 12-18 months, although axolotls in captivity may reach maturity sooner.